The present invention relates generally to inserting a secondary audio and/or video program into a real time multicast of a primary audio and/or video program. In one specific embodiment the invention relates to the insertion of advertisements, into real time multicasts of audio and/or video over the Internet.
With increased popularity and availability of the Internet, programmers, users and content providers are continuously searching for new applications of the Internet. One such application is real-time and near real-time audio and video transmitted over networks using the Internet Protocol (IP). With continued growth users will be able to view their television broadcasts and even listen to their radio programs over the Internet. While presently, the quality of the multimedia received over the Internet currently lags the quality that is received over more traditional medium, the technology is likely to soon rival existing audio/video broadcast technology.
Expanding Internet connectivity, network infrastructure improvements, and more powerful computers are all supporting this growth. Access technologies already under deployment, such as cable modems, promise enough downstream bandwidth to support real-time multimedia transport to residences. The software required to receive and render low-rate video conferences is now bundled with new personal computers or freely available (e.g., NetMeeting). Personal computers are being equipped with inexpensive native peripherals, such as DVDs, cameras, and frame grabbers, supporting content creation, capture, editing and transmission. New video standards such as MPEG-4 are also emerging and are expected to improve IP video quality. Carrier backbone transmission and switching equipment is being upgraded to keep up with increasing traffic demands and quality of service requirements. Thus growing network and computing capabilities suggest continued growth in real-time multimedia transport over IP networks.
Despite the considerable advances in network and end system technology, use of real-time IP multicast has grown at a relatively slow rate. Four reasons are typically cited for this limited growth: 1) limited available transmission bandwidth (particularly for residential users); 2) the predominance of packet loss at congested network routers; 3) the existing infrastructure""s lack of a simple, scaleable multicast routing protocol; and 4) the lack of broadcast content for users to receive. The first two factors yield what is perceived as poor reception qualityxe2x80x94for video in particular.
To address the immediate problem of poor reception, most content providers have steered clear of multicast transport. The overwhelming majority of audio content is unicast and streamed in near real time (i.e., up to a few seconds delay). This, notwithstanding that IP multicast is better suited for reaching larger audiences, exchanging certain types of personal information, and satisfying advertisers. In addition, exciting new services and opportunities are more easily achieved in a multicast setting. While packet loss recovery mechanisms in streaming transport protocols assure users of the highest quality reception, it comes at the expense of unicasting to each individual user to emulate a broadcast medium.
But, as discussed above, network infrastructure is being continuously upgraded, and routers and standards are being introduced to address existing network service quality deficiencies. These include the Reservations Protocol (xe2x80x9cRSVPxe2x80x9d) and Differentiated Services (xe2x80x9cDiffServxe2x80x9d) which attempt to achieve quality of service, and Protocol Independent Multicast (xe2x80x9cPIMxe2x80x9d) which attempts to achieve a scaleable multicast protocol described in S. Deering, et al., xe2x80x9cThe PIM Architecture for Wide Area Multicast Routing,: IEEE/ACM Transactions on Networking vol. 4 no. 2, pp. 153-62 (1996), hereby incorporated by reference as if fully set forth herein. As for lack of content, while little video is currently transmitted on the Internet, much content is potentially available. Much of this content is of interest to smaller audiences than would be efficiently targeted by other technologies such as broadcast radio or television. Hence, the technical barriers to growth in real-time multicast are being addressed, and all indications are that this trend will continue.
What limits further growth in IP multicasting, however, is the absence of a viable operational business model to justify an investment in broadcasting. Traditionally, advertisers pay for a time slot and provide a broadcaster with a pre-recorded tape of, or a disk containing an advertisement. While the content of television broadcasters can be either pre-recorded or televised live, the advertisements are broadcast by simply flipping a switch from the live camera or player feed of the feature presentation, to the player of the pre-recorded advertisement.
Streaming audio over the Internet can be expensive and presently audiences are typically small. While traditional television broadcasts and cable profit from advertisements, it is difficult to interest advertisers to pay for programs viewed by small audiences on the Internet. Clearly, solutions for effective and efficient insertion of advertisements or other programs during a real time presentation of a feature program serviced over the Internet are desired. Furthermore, a viable business model will lead to further desirable infrastructure improvements.
Consider a sporting event. The interested audience normally far exceeds the actual number of attendees. Event organizers recognize the potential value of broadcasting their content, but currently are unable to capture that value. Recording content for deferred, on-demand playback has little promise, since a sporting event""s value diminishes rapidly as results become known. In some cases, organizers might consider a real-time broadcast on the multicast backbone (MBone),. A significant barrier here is that multicasting forces the organizers to make an initial and often substantial, up-front investment. Yet no practical mechanism exists to enable the content owners to be compensated for their expense. Event organizers seek assured funding to finance broadcasting and to ensure programming quality.
Accordingly, the present invention is a system and method for supporting audio/video program insertion in real-time IP multicasts. Secondary programs are seamlessly inserted into multicast sessions of primary programs in a decentralized fashion. Relying on coordination of nodes using the Real Time Protocol (RTP) and IP multicast, inserted video and/or audio programs are displayed within the same xe2x80x98windowxe2x80x99 as the primary program regardless if the primary and secondary streams originate from physically distinct sources. If the inserted content is an advertisement, viewers have the familiar experience of commercial advertising on broadcast television.
In accordance with the present invention a primary content provider transmits its multimedia stream to a first proxy that transmits the data to a destination multicast session. A secondary content provider interested in inserting a program into that destination multicast session sends a request through a second proxy to the first proxy requesting a time slot to insert its secondary program. The request includes the duration of the secondary program. The first proxy responds with a time slot or a denial of the request depending if a time slot is available. Assuming an available time slot, at the appropriate time the first proxy transfers control of the destination multicast session to the second proxy which transmits the secondary program. Upon completion of the secondary program the second proxy returns control of the session to the first proxy. All scheduling and control transfer occurs through the development of a new protocol to manage the transfer of control. Smooth transitions occur by manipulation of the RTP header in the packets and the associated RTCP stream.
In accordance with the present invention, primary content providers, secondary content providers (e.g., advertisers) and viewers are afforded a far richer collection of relationships, opportunities and features than possible with traditional broadcast mediums. Thus for example spontaneous meetings and relationships between primary and secondary content providers may be established; program insertions may be set at arbitrary times from arbitrary locations in a multicast tree; verifiable viewer demographics from Real Time Control Protocol messages may be sent to content providers; and the system may support multiple, simultaneous program transmissions with user-selectable reception and viewing. In addition, operation of the system of the present invention does not require any modifications to existing software viewers or players.
Furthermore, the present invention is not dependent on IP being used from end-to-end, or that the network be public. Considerable applications of the system of the present invention exist outside of the Internet where IP multicast may be used on a more limited basis, such as with satellite distribution of audio/video feeds to xe2x80x9cheadendsxe2x80x9d for local internet or intranet distribution.